Olympiad Test Level 1: Environmental Issues- 2 - Class 7 MCQ

Greenhouse Effect on Earth:
The greenhouse effect is a natural process that occurs on Earth, where certain gases in the atmosphere trap heat from the sun and prevent it from escaping back into space. This process is essential for maintaining the planet's temperature and supporting life. The greenhouse effect is experienced on Earth in several ways:
1. Global warming:
- The greenhouse effect is primarily responsible for global warming.
- The greenhouse gases, such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), trap heat in the atmosphere, leading to an increase in the Earth's average temperature.
- This rise in temperature has various consequences, including melting ice caps, rising sea levels, changes in weather patterns, and the extinction of certain species.
2. Pollution:
- The greenhouse effect can be intensified by human activities that release additional greenhouse gases into the atmosphere.
- Pollution from industries, vehicles, and burning of fossil fuels contributes to the increase in greenhouse gas concentrations.
- This enhanced greenhouse effect exacerbates global warming and its associated impacts.
3. Both (a) and (b):
- The greenhouse effect is experienced on Earth through both global warming and pollution.
- The natural greenhouse effect helps maintain a habitable temperature range, but human activities have intensified it, leading to significant environmental changes.
4. None of the above:
- This option is incorrect as both global warming and pollution are directly linked to the greenhouse effect on Earth.
In conclusion, the greenhouse effect on Earth is experienced primarily through global warming, which is caused by the natural process of greenhouse gases trapping heat in the atmosphere. However, human activities and pollution have intensified this effect, leading to more significant impacts on the planet's climate and ecosystems.

Solution to decrease global warming:
There are several actions that individuals can take to help decrease global warming. Here are some detailed solutions:
1. Turn off your lights when you're not using them:
- Switch off lights in unoccupied rooms.
- Use natural light during the day.
- Replace traditional light bulbs with energy-efficient LED bulbs.
- Install motion sensor lights in areas with less frequent activity.
2. Reduce energy consumption:
- Use energy-efficient appliances and electronics.
- Unplug chargers and devices when not in use.
- Adjust thermostat settings to conserve energy.
- Insulate your home properly to reduce heating and cooling needs.
3. Minimize water usage:
- Fix leaky faucets and pipes.
- Take shorter showers and turn off the faucet while brushing teeth.
- Install water-efficient fixtures and appliances.
- Collect rainwater for outdoor use.
4. Choose eco-friendly transportation:
- Use public transportation, carpool, or bike whenever possible.
- Opt for fuel-efficient vehicles or consider electric or hybrid cars.
- Plan and combine trips to reduce unnecessary driving.
5. Support renewable energy:
- Invest in renewable energy sources like solar panels or wind turbines.
- Choose energy providers that use renewable energy sources.
- Advocate for government policies that promote clean energy.
6. Practice sustainable waste management:
- Recycle paper, plastic, glass, and metal.
- Compost organic waste instead of sending it to landfills.
- Reduce single-use plastic consumption.
- Properly dispose of hazardous materials.
7. Plant trees and support conservation:
- Plant trees in your community and participate in reforestation efforts.
- Support organizations working to protect natural habitats.
- Foster awareness about the importance of biodiversity.
Remember, small individual actions collectively make a significant impact on reducing global warming. By adopting these environmentally-friendly practices, we can contribute to a more sustainable future for our planet.

The following cannot be recycled:
- Milk cartons: Milk cartons can be recycled. They are typically made of paperboard, which is recyclable.
- Plastic water bottles: Plastic water bottles can be recycled. They are made of PET plastic, which is widely accepted for recycling.
- Glass containers: Glass containers can be recycled. Glass is 100% recyclable and can be recycled infinitely without losing its quality.
- None of the Above: This is the correct answer. All the items mentioned above can be recycled, so none of them cannot be recycled.
In conclusion, all the options mentioned (milk cartons, plastic water bottles, and glass containers) can be recycled, so the correct answer is D: None of the Above. It is important to recycle these items to reduce waste and conserve resources.

How to Keep the Environment Clean and Green
1. Use less energy:
- Reduce energy consumption at home and in the workplace by turning off lights and appliances when not in use.
- Opt for energy-efficient appliances and use renewable energy sources such as solar power.
- Insulate buildings properly to reduce the need for heating and cooling.
2. Use environmentally friendly technology:
- Choose eco-friendly alternatives to conventional products, such as biodegradable cleaning agents and recycled materials.
- Utilize energy-saving technologies, such as LED lights and energy-efficient cars.
- Support companies that prioritize sustainability and environmental protection.
3. Protect wildlife:
- Preserve natural habitats and protect biodiversity by supporting conservation efforts and participating in wildlife protection programs.
- Avoid purchasing products made from endangered species or contributing to activities that harm wildlife.
- Educate others about the importance of wildlife protection and the role it plays in maintaining a healthy ecosystem.
4. All of them:
- The best way to keep the environment clean and green is by implementing a combination of these strategies.
- Using less energy, adopting environmentally friendly technology, and protecting wildlife all contribute to a sustainable and healthy environment.
- Each of these actions has a positive impact and collectively helps to reduce pollution, conserve resources, and preserve the planet for future generations.
In conclusion, maintaining a clean and green environment requires a multifaceted approach that includes using less energy, embracing environmentally friendly technology, and protecting wildlife. By implementing these actions in our daily lives, we can contribute to the overall well-being of our planet and ensure a sustainable future.

Explanation:
The concentration of gases in our environment varies, but the gas with the highest concentration is nitrogen. Here's why:
Nitrogen:
- Nitrogen makes up about 78% of the Earth's atmosphere, which means it is the most abundant gas in our environment.
- It is an essential component of proteins and nucleic acids, which are vital for all living organisms.
- Nitrogen is relatively inert and does not easily react with other substances, making it a stable and non-reactive gas in our atmosphere.
Oxygen:
- Oxygen is the second most abundant gas in our environment, making up about 21% of the Earth's atmosphere.
- It is crucial for the survival of most living organisms as it is involved in cellular respiration, the process by which organisms convert glucose into energy.
- Oxygen is highly reactive and readily combines with other elements, which is why we often see it in the form of compounds such as water (H2O) and carbon dioxide (CO2).
Hydrogen:
- Hydrogen is the lightest and simplest element in the periodic table, but it is not as abundant as nitrogen or oxygen in our environment.
- It is primarily found in compounds such as water and organic molecules.
- Hydrogen is highly flammable and reactive, and it is often used as a fuel source or in industrial processes.
Carbon dioxide:
- Carbon dioxide makes up a very small percentage of our environment, currently around 0.04% of the Earth's atmosphere.
- It is a greenhouse gas and plays a crucial role in regulating the Earth's temperature.
- Carbon dioxide is released through natural processes like respiration and volcanic activity, as well as human activities such as burning fossil fuels.
In conclusion, while all of these gases are present in our environment, nitrogen has the highest concentration, making up approximately 78% of the Earth's atmosphere.

In our solar System, Mars and Venus show the Green House Effect, but Titan, the largest planet of Saturn and Pluto, shows the opposite phenomena which is called Anti-Green House Effect.

To conserve natural resources while traveling short distances, the best way is by cycling. Here is a detailed explanation:
Why cycling is the best way to conserve natural resources:
- Cycling is a sustainable and eco-friendly mode of transportation as it does not require any fuel consumption.
- It helps in reducing air pollution and greenhouse gas emissions, as there are no harmful emissions from cycling.
- By choosing cycling, you are reducing the demand for fossil fuels, which helps in conserving natural resources like oil and gas.
- Cycling also promotes a healthier lifestyle and physical activity, leading to personal well-being.
Benefits of cycling:
- Cycling is a cost-effective mode of transportation as it eliminates the need to spend money on fuel or public transportation.
- It allows you to avoid traffic congestion, saving both time and frustration.
- Cycling is a convenient way to travel short distances as it provides flexibility and accessibility to various locations.
- It helps in reducing noise pollution, as bicycles are much quieter compared to motorized vehicles.
Tips for cycling:
- Ensure that your bicycle is in good condition, with properly inflated tires and functioning brakes.
- Wear appropriate safety gear, such as a helmet and reflective clothing, to enhance visibility and protect yourself.
- Plan your route in advance, choosing bike-friendly paths or lanes to ensure a safe and enjoyable ride.
- Consider using a bicycle basket or panniers for carrying items, reducing the need for additional vehicles or packaging.
In conclusion, cycling is the best way to conserve natural resources while traveling short distances. It is not only environmentally friendly but also promotes personal health and well-being. By choosing cycling as a mode of transportation, you can contribute to a greener and more sustainable future.

Main Cause of Global Dimming: Aerosols
- Global dimming refers to the decrease in the amount of sunlight reaching the Earth's surface, resulting in a reduction in the amount of solar radiation.
- The main cause of global dimming is the presence of aerosols in the atmosphere.
- Aerosols are tiny solid or liquid particles suspended in the air, such as dust, soot, and pollutants.
- These aerosols can originate from both natural sources (like volcanic eruptions and dust storms) and human activities (like burning of fossil fuels, industrial emissions, and deforestation).
- Here are some key points about the role of aerosols in global dimming:
- Aerosols reflect sunlight back into space, preventing it from reaching the Earth's surface.
- They can also act as cloud condensation nuclei, leading to the formation of more and smaller cloud droplets. This increases the cloud's albedo, or reflectivity, further enhancing the reflection of solar radiation.
- The presence of aerosols in the atmosphere can also affect precipitation patterns and cloud dynamics.
- It is important to note that while global dimming may have some temporary cooling effect on the Earth's surface, it can also have negative consequences, such as disrupting weather patterns, impacting agriculture, and affecting human health.
- While other factors like biomes and acid rain can have an impact on the environment, they are not the main causes of global dimming.

Montreal Protocol and Ozone Layer Depletion:
The Montreal Protocol is an international environmental agreement that was signed in 1987. It is specifically related to the depletion of the ozone layer. Here's a detailed explanation of the relationship between the Montreal Protocol and ozone layer depletion:
Background:
- The ozone layer is a region in the Earth's stratosphere that contains a high concentration of ozone (O3) molecules.
- It plays a crucial role in protecting life on Earth by absorbing most of the Sun's harmful ultraviolet (UV) radiation.
- In the 1970s and 1980s, scientists discovered a significant decrease in ozone concentrations, particularly in the polar regions, known as the "ozone hole."
Ozone Layer Depletion:
- Ozone layer depletion is primarily caused by the release of certain human-made substances called ozone-depleting substances (ODS).
- The most well-known ODS are chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform.
- These substances contain chlorine and bromine atoms, which, when released into the atmosphere, can catalytically destroy ozone molecules.
Montreal Protocol:
- In response to the growing concern over ozone layer depletion, the international community came together to address this issue.
- The Montreal Protocol was negotiated and agreed upon to regulate the production and consumption of ODS worldwide.
- The protocol aimed to phase out the production and use of ODS by setting specific reduction targets and timetables for each substance.
- It also established a Multilateral Fund to support developing countries in transitioning away from ODS.
Success of the Montreal Protocol:
- The Montreal Protocol is widely regarded as one of the most successful international environmental agreements.
- It has led to a significant reduction in the production and consumption of ODS globally.
- As a result, the ozone layer is gradually recovering, and the size of the ozone hole has been decreasing.
- The protocol's success can be attributed to strong international cooperation, scientific research, and technological innovations.
Conclusion:
In conclusion, the Montreal Protocol is directly related to the issue of ozone layer depletion. It was designed to regulate and phase out the production and use of ozone-depleting substances worldwide. The protocol's implementation has been successful in reducing ODS emissions and facilitating the recovery of the ozone layer.

The answer is C: Saffir-Simpson.
The Saffir-Simpson scale is a special scale used to measure the intensity of hurricanes. Here's a detailed explanation:
1. Saffir-Simpson Scale:
- The Saffir-Simpson scale was developed by civil engineer Herbert Saffir and meteorologist Robert Simpson in the early 1970s.
- It is a 5-point scale that categorizes hurricanes based on their sustained wind speeds, storm surge potential, and potential damage.
- The scale helps to provide a standardized way of measuring and classifying hurricanes, allowing meteorologists and emergency officials to communicate the potential impact of a hurricane to the public.
2. Hurricane Intensity:
- Hurricanes are massive storms that form over warm ocean waters and have strong winds spiraling inward and upward at speeds of 75 to 200 mph.
- The intensity of a hurricane refers to the strength of its winds and the potential for damage it can cause.
- The stronger the winds, the more destructive the hurricane can be.
3. Saffir-Simpson Scale Categories:
- The Saffir-Simpson scale categorizes hurricanes into five categories based on their sustained wind speeds:
- Category 1: Winds of 74-95 mph. Minimal damage.
- Category 2: Winds of 96-110 mph. Moderate damage.
- Category 3: Winds of 111-129 mph. Extensive damage.
- Category 4: Winds of 130-156 mph. Extreme damage.
- Category 5: Winds of 157 mph or higher. Catastrophic damage.
4. Importance of the Scale:
- The Saffir-Simpson scale is crucial for hurricane forecasting and preparedness.
- It allows meteorologists to communicate the potential impact of a hurricane to the public in a clear and understandable way.
- It helps emergency officials and individuals to make informed decisions regarding evacuations, preparedness measures, and response efforts.
In conclusion, the Saffir-Simpson scale is the special scale used to measure the intensity of hurricanes, categorizing them based on their sustained wind speeds and potential for damage.